perf: cut nixvim build time

plugins.treesitter.grammarPackages defaulted to every grammar
nvim-treesitter ships (~350), forcing ~340 uncached
nvim-treesitter-queries-* derivations to build locally on every run.
Pin an explicit 23-language list instead.

Also disable enableMan (renders the full nixvim option reference via
options.json + nixos-render-docs on every build) and drop openscad,
which pulled in openscad, zathura + plugins, mupdf and texlive-bin.

Cold-store build plan: 370 -> ~54 derivations built,
1095 -> ~285 paths fetched (418 -> ~226 MiB).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

config/default.nix

@@ -1,6 +1,11 @@
 
-{ pkgs, ... }:
+{ config, pkgs, ... }:
 {
+  # Skip generating the nixvim options manpage. It renders the *entire* nixvim
+  # option reference on every build (options.json + nixos-render-docs + a Python
+  # env) and is pure build-time cost — `:help nixvim` is the only thing lost.
+  enableMan = false;
+
   # Extra packages available in Neovim's PATH
   extraPackages = with pkgs; [
     ripgrep     # Required by Telescope and fzf-lua for fast file content searching (grep)
@@ -35,8 +40,38 @@
     # Sidebar file explorer for visual project navigation and file management
     nvim-tree.enable = true;
 
-    # Syntax-aware highlighting, indentation, and code folding via incremental parsing
+    # Syntax-aware highlighting, indentation, and code folding via incremental parsing.
-    treesitter.enable = true;
+    # grammarPackages defaults to *every* grammar nvim-treesitter ships (~350),
+    # which forces ~340 query derivations to be built locally and pulls hundreds
+    # of MiB of parsers. Pin an explicit list instead — add languages as needed.
+    treesitter = {
+      enable = true;
+      grammarPackages = with config.plugins.treesitter.package.builtGrammars; [
+        bash
+        c
+        css
+        diff
+        dockerfile
+        git_rebase
+        gitcommit
+        html
+        javascript
+        json
+        lua
+        make
+        markdown
+        markdown_inline
+        nix
+        python
+        query
+        regex
+        toml
+        typescript
+        vim
+        vimdoc
+        yaml
+      ];
+    };
 
     # Git integration directly in the command line (:Git blame, :Git diff, :Git log, etc.)
     fugitive.enable = true;
@@ -47,9 +82,6 @@
     # Popup that shows available keybindings as you type — great for discovering and remembering mappings
     which-key.enable = true;
 
-    # Syntax highlighting and preview support for OpenSCAD 3D modeling files
-    openscad.enable = true;
-
     # Full-featured git UI inside a floating terminal — staging, committing, branching made visual
     lazygit.enable = true;